1、使用APPID和APPSecret获取access_token；

2、使用access_token获取jsapi_ticket ；

3、用时间戳、随机数、jsapi_ticket和要访问的url按照签名算法拼接字符串；

4、对第三步的字符串进行SHA1加密，得到签名。

注意事项：

1、签名用的noncestr和timestamp必须与wx.config中的nonceStr和timestamp相同。
2、签名用的url必须是调用JS接口页面的完整URL。
3、出于安全考虑，开发者必须在服务器端实现签名的逻辑。

第一步:获取access_token(需要在服务器上 )

/**
 * 微信小程序获取accessToken
 *
 * @author Mr.Wen
 * @time 2017年8月28日
 */
public class GetAccessTokenUtil {// 网页授权接口
    public final static String GetPageAccessTokenUrl = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=APPID&secret=SECRET";
    public static Map<String, String> getAccessToken(String appid, String appsecret) {String requestUrl = GetPageAccessTokenUrl.replace("APPID", appid).replace("SECRET", appsecret);
        HttpClient client = null;
        Map<String, String> result = new HashMap<String, String>();
        String accessToken = null;
        try {client = new DefaultHttpClient();
            HttpGet httpget = new HttpGet(requestUrl);
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            String response = client.execute(httpget, responseHandler);
            JSONObject OpenidJSONO = JSONObject.fromObject(response);
            accessToken = String.valueOf(OpenidJSONO.get("access_token"));
            result.put("accessToken", accessToken);
        } catch (Exception e) {e.printStackTrace();
        } finally {client.getConnectionManager().shutdown();
        }return result;
    }
}

/**
 * @author Mr.Wen
 * @description 获取ticket
 * @date 2018/3/29
 */
public class JsapiTicketUtil {// 网页授权接口
    public final static String GetPageAccessTokenUrl = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=ACCESS_TOKEN&type=jsapi";

    public static Map<String, String> JsapiTicket(String accessToken) {String requestUrl = GetPageAccessTokenUrl.replace("ACCESS_TOKEN", accessToken);
        HttpClient client = null;
        Map<String, String> result = new HashMap<String, String>();
        try {client = new DefaultHttpClient();
            HttpGet httpget = new HttpGet(requestUrl);
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            String response = client.execute(httpget, responseHandler);
            JSONObject OpenidJSONO = JSONObject.fromObject(response);
            String errcode = String.valueOf(OpenidJSONO.get("errcode"));
            String errmsg = String.valueOf(OpenidJSONO.get("errmsg"));
            String ticket = String.valueOf(OpenidJSONO.get("ticket"));
            String expires_in = String.valueOf(OpenidJSONO.get("expires_in"));
            result.put("errcode", errcode);
            result.put("errmsg", errmsg);
            result.put("ticket", ticket);
            result.put("expires_in", expires_in);
        } catch (Exception e) {e.printStackTrace();
        } finally {client.getConnectionManager().shutdown();
        }return result;
    }
}